In recent years, various devices have been developed which allow users to enjoy popular sports games, such as baseball, soccer, basketball and golf, in rooms or in specific places through simulation in the form of interactive sports games.
Particularly, in recent years, a so-called screen golf system has been developed in which, when a user swings a golf club to hit a golf ball placed on a hitting mat, a sensing device senses the hit golf ball to extract physical information on the moving golf ball so that the trajectory of the golf ball can be simulated on a virtual golf course, thereby allowing the user to enjoy golf in virtual reality.
In order to simulate sports using balls, such as golf balls, in such interactive sports games, much research has been conducted into various sensing systems for accurately sensing physical information on a moving ball, i.e. movement of a ball.
For example, various sensing devices, such as a sensing device using an infrared sensor, a sensing device using a laser sensor, a sensing device using an acoustic sensor and a sensing device using a camera sensor, have come onto the market. Much research has been conducted into a camera sensor type sensing device for acquiring and analyzing an image of a moving ball to accurately sense a state of the moving ball.
In the camera sensor type sensing device, however, an ultrahigh-speed camera having a high resolution is necessary for accurate sensing, which greatly increases costs of the sensing device. On the other hand, if a camera having a relatively low resolution and a relatively low speed is used, the quality of an image acquired by the camera is low with the result that it is very difficult to accurately extract and analyze a ball or a golf club from the acquired image, and therefore, it is very difficult to derive physical properties of the moving ball. In particular, it is very difficult to measure spin of the ball.